Solved! What Causes Low Water Pressure—and How to Fix It

If you feel that your home’s water pressure is subpar, use our guide to determine what’s to blame and find out how you can fix it.

What Causes Low Water Pressure? 4 Potential Problems

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Q: I have always had good water pressure throughout my home, but recently I noticed that the water pressure has dropped, and I am concerned that it will only get worse. What causes low water pressure? Can I remedy it myself?

A: The average water pressure at the inlet valve to a home should be about 40 to 50 psi, but your home may still experience a lower water pressure than ideal for any number of reasons. Where you notice it can help to determine the cause of the trouble and whether or not you can fix it yourself. For instance, low water pressure throughout your neighborhood is likely an issue that needs to be dealt with by the government or local utility, while low water pressure at a specific appliance can normally be traced back to a clogged aerator or a leak in the water line running to the appliance. Ahead, we will look at what causes low water pressure and how to remedy the problem throughout your home.

What Causes Low Water Pressure? Appliances in Use

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Too many appliances using water at once causes low water pressure, so consider how you schedule your day.

Depending on the time of day that you experience low water pressure, there may be a higher than average need for water in your home. The more appliances that are using water at one, the less water there will be for all applications. While this is not necessarily noticeable with two, or even three appliances running at the same time, the fact remains that the more appliances used simultaneously, the lower the resulting water pressure.

The simplest solution for this situation is to stagger your water needs throughout the day. If you need to shower at 8am, wait until 9am to start the dishwasher. If you need to wash laundry, but the lawn also needs to be watered, consider washing laundry during the day and watering the lawn at night, when it will do the best. Watering your lawn during the coolest hours of the day will help your grass absorb more water in a shorter period of time. For more on when to water your lawn, see our guide to the best time to water your grass.

What Causes Low Water Pressure? A Partially Closed Shutoff Valve

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Confirm that the home’s main water shutoff valve is fully open.

The main water shutoff valve controls the flow of water into your home. If your valve has recently been used during a minor plumbing repair, there is a good chance that it has not been fully opened. This means that the full pressure of your water system is being reduced by a partially closed valve.

Locate your main water shutoff, normally installed immediately after your water line enters your home. Depending on the style of valve you have installed, you may see a lever that only moves 90 degrees or a handle that turns like a wheel. Reopen using one of these two methods:

  • To fully open the lever style of valve, you will move the handle of the valve so that it lays in line with the water pipe.
  • To fully open the handle style of valve, you will turn it counter-clockwise until it can no longer turn. Then, to avoid potential leaks or a seized (or stuck) valve, turn this style of valve a quarter turn back in the clockwise direction.

If your home utilizes a pressure regulator, check that it’s fully operational.

Some homes in areas that experience higher than average water pressure will have a pressure regulator installed immediately after the main shutoff valve to ensure that the plumbing fixtures and pipes within the home are not damaged by exceedingly high water pressure. Water pressure beyond the normal psi for a residential home strains the water system’s fixtures and valves beyond their functionality and can cause the fixtures to break and cause a massive amount of water damage, if not contained. If you have a regulator in your home, your low water pressure may be due to the regulator’s current setting, or the regulator may be broken, resulting in higher or lower water pressure than normal.

Check the setting on your pressure regulator to determine if it is set to about 50 psi, which is the usual default setting for regulators. If it is not, you can adjust this on your own, or contact a plumber to adjust it for you. If it is already set to 50 psi, you may need to have a plumber come in and replace the faulty regulator.



What Causes Low Water Pressure? Sediment and Debris Buildup

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Call a plumber if you suspect debris buildup to be a problem.

If you have verified that your main valve and regulator are functioning correctly, then you may be encountering debris buildup. Over time, calcium salts, magnesium salts, and other soluble mineral compounds can begin to accumulate in our water pipes. This can occur at a much faster rate in areas with hard water than in areas with average or soft water because of a high occurrence of calcium and magnesium salts in hard water regions. However, hard water is not the only issue that can impact the rate of debris buildup. Materials that have been shown to corrode significantly over time, such as lead or galvanized steel, will increase the rate of debris buildup in your pipes because the debris clings to the irregular material. Additionally, if your plumbing system is regularly left sitting for weeks or months at a time without use, debris will naturally settle and accumulate.

A plumber can help you identify the exact area that is preventing water flow and replace this section of the pipe. Or, if you have hard water, you may consider replacing your existing fixtures with ones that are designed for hard water applications so that you can avoid as much buildup as possible. However, if this problem has occurred once, it is likely to occur again, so you may wish to think bigger. Investing in a new water line is one possible way to help prevent this situation from recurring anywhere in the house, but it may be too costly for an intermittent issue.

RELATED: 15 Problems Hard Water Can Cause

It is important to understand the frequency and severity of your issue to determine what you are willing to do to resolve the situation. Costs to replace your service line can range greatly depending on the diameter of the pipe entering the house, the material used, and the length of the pipe required. On average, the replacement of your water line will cost approximately $2250. Replacement of your plumbing fixtures might sound like a significantly cheaper solution, but they could total to more depending on the type and number of fixtures requiring replacement. On average, the cost of replacing a fixture or a small section of pipe can range from $300 to $1800 per fixture, while installing a water softener costs approximately $500 to $2500, on average. Known hard water locations are also far more likely to have government programs that are intended to help homeowners pay for these upgrades.

A corroded water line will also lower water pressure throughout the home.

Certain water line materials will corrode from within, creating a gooey buildup that reduces water flow and potentially causing leaks that lead to lower water pressure in your home. Lead and galvanized steel water lines are notorious for being slowly corroded by the water that runs through them—these may even collapse in on themselves if there is a rapid change to the water pressure, such as closing the main valve and opening it quickly.

The best possible solution, especially if you have lead water lines which can leach into your drinking water, is to consult with a professional plumbing company and determine if replacing your water lines with a better material, such as copper, will resolve the issue. While this will likely be a costly solution, the alternative can be far more expensive if your water line eventually gives out and damages the interior of your home. To make this resolution less costly, you can look into government-funded programs that are intended to help with the replacement of service lines, such as the Environmental Protection Agency‘s lead service line replacement program, or local programs like that provided by the Massachusetts Water Resources Authority.